Semi-automatic telephone system.



T. G. MARTIN.

SEMI-AUTOMATIC TELHHONE SYSTEM.

APPLICATION FILED MAR. a. 1911. RENEWED MAY 2av l9l7.

Patented May 7,1918.

7 SHEETS-SHEET 1.

T. G. MARTIN. SEMI-AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED HAR- 3.mi, RENEWED MAY 21;. m1.

1 ,265,225. I Patented May 7,1918.

1 lHEETl-SHEET '2.

6 E g. K

% OR V5 1 1 T. G. MARTIN.

SEMI-AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED "AR- 3. NH!- RENEWED MAY 28,1917.

Patented May 7,1918.

T. G. MARTIN.

SEMI-AUTOMATG'TELEPHQNESYSTEM. APPLICATION FILED MAR. 3- IQH- RENEWEDMAY 28. 1911.

1,265,225. Patented May 7, 1918 1 sun's-sun 4i 1 IIIIIIIIIIIIHh-W/TNZIFSES a f/W E/WOR:

mm. 7whtm TTOR/VELZ T. G. MARTIN.

SEMI-AUTOMATIC TELEPHONE SYSTEM.

APPQICATION FILEDMAR. 3. 19H. RENEWED MAY 28, m1.

1,265,225. Patented May 7, 1918.

ISHEETS-SHEET 5- EMT/1455559 AWE/V703:

T. G. MARTIN.

SEMI-AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED NM. 3. 1911. RENEWEDE28. 1911.

1 ,265,225. Pamnted -May 7,1918.

7 SHEETS-SHEET 6- 17NE5355 Jan/wok.- a. W. 7W1? 944 M T. G. MARTIN.

SEMI-AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAR. 3. I91]. RENEWED MAY 28.1911.

1,265,225. Patented May 7,1918.

TSHEETS-SHEET 7'- KI) g? g *i L Mam/52555 MENTOR:

flan/{MM- 4 TMQ flTTOR VEYS UNITED STATES PATENT OFFICE.

TALBOT G. MARTIN, OF CHICAGO, ILLINoIs, ASSIGNOR To AUTOMATIC ELECTRICCom v PANY, -01 CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS. I

SEMLAUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Application filed March 3, 1911, Serial No. 612,084. Renewed May 28,1917. Serial No. 171,584.

To all whom it may concern I Be it known that I, TALBOT G. MARTIN, acitizen of the United States of America, and resident of Chicago, Cookcounty, Illinois, have invented a certain new and useful Improvement inSemi Automatic Telephone Systems, of which the following is aspecification.

My invention relates to telephone systems of that kind in which anoperator must answer calls from lines of different character that is tosay, from lines some of which are equipped for measured service, andsome of which are equipped for unmeasured service, or which differ inany other manner, requiring that the operator must find out from wherethe call comes before it can be prop' erly extended, which isparticularly essen tial in a semi-automatic system.

My invention contemplates, therefore, a system in which means areprovided for automatically indicating to the operator the character ofthe line calling.

It contemplates, moreover, a system of this ,kind in which the signalthat indicates the character of the calling line is given the operatorat the time the call is answered.

Thus the Operator knows immediately whether the call is, for example,from a measured service line or from an unmeasured service line, or fromsome other kind of line, there being as many different indicatingexpedients as llllGIQs-fiJ-ffi different kinds of lines.

The nature and advantages of my invention will, however, hereinaftermore fully appear.

In the accompanying drawings Figures 1,2, 4:, 5 and 6 taken togetherrepresent a complete connection. between a manual substation A (Fig. 1)and an automatic substation sA (Fig. 6) in a system embodying theprinciples of my invention. Fig. 1 also shows apparatus by means ofwhich the subscriber at substation A may obtain connection with asubscriber at another substation ofthesame kind. Figs. 6 and 3 showapparatus by means of which the subscriber at the automatic substation Amay communicate with an operator for the purposeof requesting aconnection with a line in some other exchange. Fig. 7 is a diagrammaticillustration of the master switch D of FigQ 1. Figs. 8 and 9 show aconnection established between two substations A and A" through themedium of apparatus similar to that shown in Fig. 1.

In Fig. l the line of the substation A is equipped at the central oflicewith the usual multiple jacks j and j; but, instead of being providedwith the usual answeringjack, is provided with an automatic trunkingswitch C. This automatic switch C, together with a number of othersimilar switches, has access to a number of trunk lines each of whichleads to a so-called secondary trunking switch C. These secondarytrunking switches are usually arranged in groups, and the trunk linesleading from each group of primary trunking switches are distributedamong the different groups of secondary switches.

Each group of secondary switches has access to trunk lines which lead tooperators trunk lines terminating in plugs P. With thisarrangement anumber of plugs may be made common to all of the substations A in theexchange. Any subscriber at a substation A, wishing to make a call,simply removes his receiver, whereupon the switches C and Cautomatically operate to extend his line to one of the plugs P and tosignal the operator. The operator completes the connection by insertingthe plug P into a-multiple jack of the line called forthat is, providedsaid'line is a manual line similar to the line A. It the line called forshould be a line of an automatic exchange, such 'as the substation A(Fig. 6) the plug P of a cord 0 (Fig. 2) would be inserted intoa jack J2 of a trunk line leading to the automatic exchange, and the automaticsubscriber would be'called in the usual manner. The plug P (Fig. l) ofthe cord 0 is then inserted into a jack of the'calling line.

The automatic substation A (Fig. 6) has allotted to it at the centralofiice the primary trunking switch C 'If the subscriber at substation Awishes to call one of the manual substations A he operates the primaryand secondary switches C and C the repe'ater E and selector F (Fig. 3)to extend his connection to an operators trunk circuit H. No connectionis made through this trunk, however, but the operator is simply giventhe order over it. The calling sub-' s'c'riber then hangs up. hisreceiver and breaks connection with the trunk H. The operator then callsback to the callin line b'yinserting the plug P of the cord Patented May7, 1918? change and operating the switches to conmeet with the callingline, and then the operator inserts the plug P" ofsaid cord into a jackof the called .line.

The manual substation A may be of any suitable type, and, as shownherein, it comprises the usual receiver 2, transmitter 3, ringer 4,condenser 5 and switch hook 6.

The trunking switch C, as shown, is of the general type disclosed inBritish Patent No. 26,301 of 1906, and in the American Telephone Journalof New York, N. Y., of June 6, 1908, being ofa somewhat modifiedconstruction. The switch C comprises the usual plunger 7 (Fig. 7)attached to the end of the plunger arm 8. The plunger arm 8, togetherwith the relay armatures 9 and 10, is controlled by the magnet 11. Themagnet 11 comprises four windings, namely, a so-called pull-in winding12, a holding and cut-ofl winding 13, line winding 14 and an auxiliarywinding 15. The core of the magnet is provided near the center of itslength with a lateral projectionlti by means of which the magnet isattached to the bracket 17 upon which the armatures 8, 9 and 10 arepivoted. \Vith this method of mounting the magnet, the magnetic circuitof the windings 12 and 13 is maintained separate from that of thewindings 1e and 15, so that the armatures upon one end of the magnet arenot affected by the windings upon the other end. Of the two windingsupon the upper end of the magnet only'the winding 12 is strong enough toattract the plunger arm '8 from its normal position. The winding 13 isstrong enough, however, to hold the plunger arm in its operated positionafter it-has once been pulled down, When the plunger arm is pulled downit forces the plunger into abank of contact springs in the usual manner.forcing springs 20, 21. 22, 23, 24, 25, 26 and 27 into contact in pairsThe secondary switch C is Simi, lar to the switch C except that ithasonly two'windings, namely, a pull-in Winding 28 and a holding winding29.

The master switch D which controls the plungers of a group of lineswitches C is of the general type disclosed in said British Patent#26301 and American Telephone J oumal, being of a somewhat modifiedconstruction, asshown in Fig. 7. The master switch consists essentiallyof a motor magnet 30 for driving the ratchet wheel 31. The ratchet wheel31 is connected with the shaft 32 by means of a link 3.3 in such amanner that a rotary motion of the ratchet wheel is transmitted to theplunger shaft 34, giving to it an oscillatory motion about the shaft 32so as to move the idle plungers back and forth in front of theirtrunk'terininals. To the shaft 32 there is secured a locking late 35-provided near its outer edge with a number of openings 36 whi h trolledthrough are adapted to be engaged by a pin 37 upon the end of thearmature 38 of relay 39. These openings are so spaced that the pin 37can on go one of. themonly when the plungers t at are engaged with theplunger shaft are directly in front of the correspondingtrunk termlnal.The master switch is. also provided with a bank ofcontacts comrising acommon segment 311, and one ividual segment a for each trunk line towhich the switch 0 has access.

The operators cord 0 (Fig. 2.) is similar to the usual operators cordused in manual switch-board practice, the supervisory cit-- cuits beingespecially adapted to the. systemv shown herein. The superiii'soryrelay-401s a polarized rela and-consecfuently wi 1019 9 the circuit ofamp 41 on y'when current flowsthrough the relay 40 in a certain di-'rection. f

' The selector F (Fig. 3) is of the ggneral type disclosed inUnitedstates Letters Patent #815,321, granted March '13,, 190.6, toKeith, Erickson and Eriokso being somewhat modified'hpwever, in or, erto o e r ate in a. two-wire system. Among other etails it comprises theusual wipers 42, 43 and 44 carried 11 on a shaft (not shown) which has avert ica motion controlled by the rertical magnet i5. and, a rotarymotion controlled b-y'the rotary magnet 46. The usual side switchcomprising the wipers 47 and 48, is controlled by the private magnet 49in the usual manner. Means for restoring the switch to normal positionis provided in the release magnet 50. As long as the switch shaft isinitslowest position the circuit of the release magnet is opened at thesprings 51. which are so 'arated by the arm 52 which is attached tot eswitch shaft. The mechanism of the switch is released immediately uponthe energization of the release magnet, rather than by itsdeenergization as shown in said selector patent. The switch is conthe.medium of, the doublewound line re a 53. The relays 54 and 313 areslow-acting, 0., slow to deenergize when their circuits are broken. Theprivate magnet 49 is controlled b the rotary ,magnet 46 electricallythrong the medium of the contact point 310 instead of mechani- (sally,as is s own'in the selector patent referred to.

i The operators trunk His in the nature or a so -called recordin tolltrunk, z. 6.,1t is for use in giving or ers to the operator and not foractuallymaking connections.

The selector F? (Fig. 4) is similar, to the selector F (Fig. 3).

The apparatus shown at E (Fig. 4) is a 125 repeater for repeatingimpulses from one At M (Fig. 5) there is shown a ringing currentgenerator, and at N is represented a busy line signaling machinecomprising a current interrupter 71 and a transformer or induction coil72.

The automatic substation A (Fig. 6)

comprises the usual receiver 73, transmitter 74, rin er 75, condenser 76andswitch hook 312. ince it is an automatic substation it is alsorovided with an impulse wheel 77 attache to a shaft7 8 to which thereisalso secured a dial (not shown) provided with finger holes. upon itsperiphery with a number 0 impulse teeth which are so arranged that asthe impulse wheel returns to normal position, after having been rotatedthrough the medium of the dial, each tooth that passes the end ofimpulse spring 7 9 forces said spring-out of en agement with the spring80. g

ilaving given a general description of the apparatus I will nowexplainin detail the manner in which connections are established between thevarious'lines, showing how the operator is enabled to identify thecharacter of the lines. hen the subscriber at substation A wishes tomake a call he does so,

by removing his receiver from the switch hook in the usual manner@ Thehook theresprings 82 and 83, line 84, receiver 2, transmitter 3, springs81 and 6, line 87, springs 85 and 86 and line winding 14 ofswitch C tobattery lead 90, thence through the battery B to groundG. The winding 14there upon attracts the armature 10, which operates to close a circuitfrom ground G through springs 82 and 88, windings 12 and 15, contactpoint 91 and armature 38 to the battery lead 90. The winding 12thereupon attracts'the plunger arm 8 and cut-off armature 9. The plungerarm operates to cause the plunger to "press the bank springs 2027together, as previously explained, while the armature 9 operates todisconnect the ground G and line winding 14 from the line. The

- armature 1O doesnot tall back and break the circuit of windin'immediately upon the 'deenergization 0 line winding 14, because theplunger arm short-circuits the auxiliary winding 15 at thesprings 92 and93, thereby The impulse wheel is Provided causing said winding todeenergize slowly and hold, u the armature 10 for an instant. This provies time for the circuit of winding 13 to be closed before the winding 12is denergized'. The winding 13 is energized as follows: When the banksprings 26 and 27 are forced into contact bythe plunger of switch 0 avcircuit 'is closed from ground Gr through said springs, winding 28 ofswitch C, springs 94 and 95 and armatures96,97 and 98 to the batterylead 90. The winding 28 attracts the plungerarm 99, which operates toclose the bank springs in the switch .C, and also to-shift spring 94 outof engagement with spring 95 and into contact With spring100,'Wherebv"the winding 28 is connected to battery through the winding29, thus establishing a holding circuit for the switch Cf independent ofthe contacts of the relays of themaster switch D. The combinedoperations ofthe switches C and C extend the line connection to a trunkline leading to a plug P. whereupon the relay 101 becomes energized.overa circuit extending from ground G through the lower winding ofsaidrelayp bank springs 102, 103, 23

and 22-,line 84, substation A, line 87, springs 20. 21, 104' and 105 andupper-winding of relay: 101 to the battery. The relay 101, uponenergizing, operates tocoinplete a circuit from ground G through themiddle winding-of relaylOl, springs 106 and 107, 108 and 109. banksprings 110 and 111, 25 and 24, winding 13 and secondary winding of theinduction coil 112- to battery. As before explained, this circuitthrough the winding 13 is closed before the circuit of winding 12 isbroken. and thereforeihe plunger arm remainsin its operatedposition. Therelay 101, upon energizing, also con'lplete'shicircuit from ground Gthrough springs 114 and 115,116 and 117 and lamp 118 to battery, wherebythe operator is sig naled; 'The operator answers by throwing the key Kto bridgethe talking set S across the line. v

The manner in whichthe operator is enabled to identify the character ofthe calling line is as follows: It will be remembered that the circuitof the holding windin 13 of-syvitch C includes the secondary win ing ofthe induction coil 1 12 and also a winding of relay 101; This winding onthe rel 73101 has a low number of ampere turns an alimewill notoperatively energize the relay, but 120 it affords an inductiveconnection between the circuit of secondary winding of induction coil112 and the line circuit. The pri mary. winding of the induction coil112 is connected'to. an alternating current geuerator. and thereforewhen the operator connects her'talking set with the line she will. hearatone which will indicate that the calling line is of a. certaincharacter. If there are only two different kinds of lines to bedistinguished between, the cut-oil windings of one kind may be connectedto battery through an induct1on coil, as shown, while this inductioncoil maybe omitted from the other lines. If there are more than twokinds of lines, tone tests of difi'erent characters may be used, one foreach class of lines; These difi'erent tone tests may be produced byinterrupting the tone test current for the different kinds of lines atdifferent intervals, or in any other of the well known ways.

Returning now to the operation of the line switch C, it will be seenthat when the bank springs 26 and 27 are forced into contact, a circuitis completed from ground Gr through said springs, conductor 119, contact120,-

wiper 121, segment 311 and relay 122 .to battery. The relay 122, uponenergizing, completes the circuit of relay 39, which operates towithdraw the pin 37 from the plate 35 and close the circuit of the motormagnet 30. This circuit extends from ground G through motor. "magnet 30,springs 123, contact point 124 and armature 38 to battery. The motormagnet'then begins to operate in a manner similar to that of a buzzer tomove the plilngers of the idle switches away from the trunk seized.Shortly after the master switch begins to operate, the wiper 121-passesoil the contact 120 and the relays 122 and 39 deenergize. The masterswitch continues to operate, however, until the next opening passesunder pin 37.. If the trunk correspondin to this opening is idle, thepin 37 .drops mto it and permits the armature 38 to disengage thecontact point 124 .to break the circuit of the motor magnet. .If thistrunk is busy, however, the wiper 121 finds the corresponding contactgrounded and the relays 122 and 39 remain energized until the nextopening has passed the pin .37 and the plu rs are carried past the busytrunk (or tru to an idle one.

When the line switch C operates, the master switch D operates in thesame manner as the master switch D 'to advance the plungers of the idleswitches C to an idle trunk. It will be noted that the armature of rela125, which corresponds to relay 122 of t e master switch D, controls,through a back contact, the circuit of a slow acting relay 126.. If theplungers of the switches C do not pass any busy trunks, the circuit ofrelay 126 is not broken lon permit its armature to fall bac If, however,the plungers do have to pass idle trunks, the relay 125 remainsenergized long enough to cause rela 126 to deenergize. Whenthe'armatureo relay 126 falls back it disconnects the pull-in windings of all theswitches C which are controlledby master switch D from battery, andextends a guarding potential from the ound G through the Win 1: 28 ofthei le switches enough to.

O to the contacts in the. banks of the master switches D correspondintothe trunks leading to the said switches thereby preventing the masterswitches D from stopping on said trunks. Thus no connection will beextended to a secondary switch while its plunger is in motion. Any callcoming in at this time will be diverted to a grou of'secondary switcheswhose master switc is not ,operatin' It should be stated that althoughthe re 'ay 122 of master switch D will energize in series with thewinding 28 of switch C, said switch will not beoperated, due to thecomparatively high resist= ance of relay 122.

Each of the trunks leading from the switches C is provided with a relay127.

When all these trunks in one grou become to the calling line A, the plugP is sim 1y insertedjinto a multiple jack of the cal ed line. When theplug P is removed from its seat the springs 130 engage, whereby a .cir-.

cuit is completed through relay 131, which operates to remove the testtone current from the middle winding of relay 101, to ground winding 13of switch C direct, to open the circuit of lamp 118 and close thecircuit of lamp 132. This circuit extends from ground G through springs114, 133, 134 and'135 and lamp 132 to battery. When the plug insertedinto the jack of the called line the cut-off winding of its line switchC is energized. This willbe explained in connection with line A.

Itjvill be seen that when a plug is inserted into a multiple jackof'sucha line the springs 136 and 137 are forced into contact, wherebythe circuit of winding 13 is closed.

P is.

The armature 9 is thereupon attracted and moves his receiver, said lineis provided with talking battery current through the windings of therelay 139, which energizes and extinguishes'the lamp 132. When thecalled subscriber hangs up his receiver therelay 139 deenergizes again,lighting the lamp 182,.whic'h es the operator a disconnect steps. U Therelay 163, which is inc signal. When the calling subscriber hangs up hisreceiver the relay 101 deenergizes, and

" relays deenergize, the winding 13 of the switch is deenergized. andthe-plunger of said switch restores to normal position,

breaking the ci'rcuit'of the switch C, which thereupon restores also. y

In case the subscriber at substationAdesires connection with asubscriber of the automatic exchange, he hangs up his receiver aftergiving the operator his ownnu'mber and the number of the line desired,whereupon the switches C and C' release in the manner just described,The lug l? of the cord 0 is then inserted into is e ack J and the key Kis operated to bridge the calling device (springs141 and 142) across theline. When this occurs a circuit is closed from ground Gr through thelower winding of the relay 143 ofthe selector F (Fig. 4), springs 144and 145, conductor 147 ,sleeve conductors of the jack J and plug Psprings 149 and 150, impulse springs 142 and 141, springs 151 and 152,tip of the plug P 'and jack J conductor 148, springs 153 and 154 andupper winding 01; relay 143 to battery lead 156. The relay, 143, uponenergizing, compl etes a circuit from ground G through springs 157 and158 and relay 159 to. batter lead 156. The operator now operates the caling device. for'the first digit of the number of the called substationA #220. The circuit oi the select'or line relay 143 ismomentarily brokentwiceat the impulse springs 141 and 142 in response to this operation ofthe calling de- :vice. -The relay 159 of the selector, being slowacting, does not deenergize during the.

momentary interruptionof its circuitby the relay 143; consequently, eachtime said relay 143 dei nergizes it. closes a circuit through the.vertical magnet 165. This" circuit exlead 156. The verticalmagnetoperates in res'ponseqto 'theztwo impulses received over this circuit toraise the shaft and wi e'rs" two l uded in circuitw-iththe verticalmagnet, is energized bythe first impulse, but being a slow acting re'laydoes-notallow its armature to fall bac until after the last impulse hasbeen deliver-ed. In its energized position the relay 163 closes.acircuit'from ground ,G" through springs 1-67 and 168 .and privatemagnet 169 to batteryxlead 156. This circuit is broken when the relay163. deenergizes after the lastimpulse has beendeliveredto the verticalmagnetgxand the private magnet thereupon dcenergizes also and permitsthe side sw tch to pass to second position. Inpassing from first tosecond position the side switch wiper 164 the'battery iron: the yerticalmagnet and closes a circuit through the rotary magnet 170. This circuitextends from ground G through the interrupter springs 171, magnet-170.an d side switch wiper 164 to battery lead'156, The rotary magnet17 0 will then continue to operate in a manner similar to that of abuzzer to rotate the 17 6, side switch wiper 177 and magnet 169 towipers step by step as long as the side switch remains in secondposition. As soon as the rotary magnet energizes the first time, acircuit is closed from ground Gr through contact point 17 3, armature174 and private magnet 169 to battery. The private magnetis energizedover this circuit and is again deenergi'zed when the rotary magnetdeenergizes after having rotated the wipers the first step, provided thefirst trunk line upon which the selector wipers are rotated is idle. Ifthis trunkis busy, however, the private wiper 176 finds the contactwhich it engages provided with a guarding ground potential. A newcircuit is then closed through the private magnet extending from saidgrounded contact through the wiper battery lead 156. .The private magnetthen i does not deenergize when the rotary magnet armature falls baclr,and the side switch is locked in second position. .net then continues toadvance the wipersv The rotary magstep by step until the contacts of anidler trunk are reached, whereu on the private magnet deenergizes,permitting the side switch to pass to third position and break 'gizing,operates to disconnect the line relay 143 from the line and to extendthe connection through the wipers 181 and 182 to the repeater E. Whenthe circuit isthus extended to. the repeater its line relay 183 isenergized over a circuit extending from ground Gr through the lowerwinding of said relay, sprimgs 184 and 185, selector wiper 182, springs146 and 145 conductor 147, thence through the operators calling deviceand back through the conductor 148, springs 153 and 155, wi er 181,springs 186 and 187 and upper win ing of relay to battery. The relay183, upon energizing, closes a circuit'from ground G through springs 188and 189 and relay 190 to battery lead 156).- The relay 190, upon,energiziug, providesa new circuit for the relay 180 of the selector Fextending from ground G through the right-hand winding of c011 191,springs 192 and 193, 194 and 195, bank contact 196, rivate wiper 176,side switch wiper 177, re a 180 and side switch wiper 164t0 jbatter-yead 156. This circuit maingization of the line relay 70 of theconnectorthe slow-acting relay 159. The trunk leading to therepeater Eis also protected from seizure over any of its multiple contacts bystructed and adjusted thati t cannotbeoperatively energized by onewinding alone, but requires the combined energization of both itswindings to cause it to attract its armature.

The engagement of springs 198 and 199', upon the energization of therepeater line relay .183, closesa circuit through the line relay 70 ofthe connector L (Fig. 5), said circuit extending from ground -G15through.

the lower winding of said relay, springs 207 and 206, conductor 211,springs 1-98 and 199,

left-hand Winding of impedance coil 191,

right-hand winding ofrelay 197, conductor 212, springs 203 and 204 andupper winding of relay 70 to battery. Although-both wind ings of therelay 197 ofthe repeater now carry current, the relay is not operatedbecause the current flows through the two windings in oppositedirections. The enerservesto close a circuit through the slow actingrelay 215. This circuit-extends from ground Gr through springs 216 and217 and relay 215 to battery lead 227.

The apparatus is now in position for the reception of impulses for thesecond digit 2. The line relay 1830f the repeater E is deenergized twiceby the impulses for this digit, each time breaking the circuit of theconnector line relay at the springs 198 and 199. The relay 190, beingslow acting, does not denergize between impulses; conse quently, eachtime the relay 183 deenergizes it also closes a circuit from ground Gthrough springs 188 and 219, springs 220 and 2 21 and relay 222 to thebattery lead 156. The rela '222'is energized by the first impulse anremaiiis in its energized position until after the last impulse has beendelivered. In its energized position the relay 222 disconnects thecondensers 55 and 56 from the trunk lines 211 and 212, and shortcircuits the right hand winding of relay 197 and lefthand winding ofcoil 191 to remove their resistance from. the circuit of the connectorline relay while it is operating- Each time the line relay 70 of theconnector'denergizes in response to the breaking of its circuit by theline relay of the repeater, a circuit is closed'from ground G throughsprings 216 and223, springs 22% and 225 (the slow relay Another resultof the energi ees-eat 215 remains energized between impulses), relay226, vertical magnet 60 and side switch wiper 69 to the battery lead227. The vertical magnet is energized twipe over this circuit andoperates to raise the shaft two steps.-

When the operators calling device is operated for the last digit Otherepeater E opcrates in the same manner as tor the-previous digit, exceptthat ten impulses instead of two are repeated to the connector L. Eachtime the connector line relay 70 deenergizes in response to theimpulses, a circuit is closed from ground G through springs 216 and 223,224 and 225, relay 226, springs 229 and 230, rotary magnet 61 and sideswitch wiper 69 to battery. The rotary magnet is energized ten timesover this circuit and operates to rotate the Wipers onto the contacts ofthe desiredline. The relay 226 operates in the same manner as for theprevious digit to close the circuit of the private magnet 62 while therotary magnet is operating. If the called line is idle the privatemagnet deenergizes when its circuit is broken by the relay 226 after thelast impulse is delivered to the rotary magnet, and the side switchpasses to third position, completin the connection with the called line(Fig. 6 through the side switch wipers 66 and 67, shaft wipers 57 and 58and conductors 231 and 232. The movement of side switch wiper 68 tothird position provides a guarding potential for the connector prlvatebank contacts of the called line, and closes an energizing circuit forthe cut-off winding of the line switch C This circuit extends fromground G through the right-hand winding of the bacl -briclge relay 65,springs 210 and 209, side-switch wiper 6'8 and private wiper 59- toprivate bank contact 233 andthence to the corresponding contact in thebanl: of each connector which has access to the line #220. From contact233 the circuit extends farther over conductor 234, through the winding235 of switch C and through the secondary winding of the tone tcstinduction coil 236 to battery lead 227. The winding 235,'uponenergizing, operates to disconnect the switch C from the line. Thecircuit of the winding 235 includes the secondary winding of theinduction coil and the right-hand winding of the back-"hridge relay amus65. This. winding of the. relay 65 has alqw resistance and a smallnumber of turns, and therefore does not cause the relay to operate, norinterfere with the energization of the vcut-oil winding 235. The onlyfunction of this third winding on the relay 65 is to furnish aninductive connection between the circuit. of the identifying .tone test.induction coil 236and theline'circuit, which connection is obtainedthrough the medium of the other two windings of the relay 65, which areconnected with the-line. Thus, if the operator throws thekeyKf in theopposite direction and bridges the talking set across.

the line after the calling device has been operated for the last; digit,she-is enabled to identify the character of the line called;

At the instant the side switchwiper 69 of the connector L reaches thirdposition acircuit is closed from ground G'-' throughinterrupter "-237,ringer relay 64, springs .238

and 239 and wiper 69 to battery. .-Sinee this circuit includes theinterrupter 237,'the relay 64= is' energized intermittently, each; timeoperatlng to close a signaling circuit from one terminal of thegenerator M through springs 240 and 241, wiper 57, conductor 231,springs 242 and 243, line 244, ringer 7 5, condenser 7 6, springs 245.and .246, line.

.A and throughthe springs 246 and 252, re-

ceiver 73 and transmitter 74 and back over the other side'ot the linetothe connector, throughringer relay springs 241 and 253,-

private magnet sprln s .254 and left-hand vwinding ofirelay 65 to atterylead 227. The

relay 65 ,'upon energizing, operatesto' cut its right-hand winding 03circuit at springs 208,209 and 210 to remove the test tone ifrorn theline. The closure of vspri n 200; and 201 closes Y a circuit; fromground through springs.208 and 209, side switch wiper-68,

.springs 200 and .201. and relay 256 to battery lead 227.. The relay256, upon energizing,

- opensthe circuit of the rin er relay and forms a; lockingcircuit for,ltself through springs 257- and 258 so that the circuit of the relay 64cannot be closed again before the connection is released. The shifti ofthe springs 206 and 203 of the backrbridge relay "transposes theconnections between the windings o' f the line relay and the trunkconductors 211'and'212, whereby the .current in the line between therepeater and connector is ,rer e'rsed in direction.- This re-. vers'al.of the current causes the, two windings of r'elay 197' of the repeater Eto asslst .e eh-..o he. whe bya h i y is ene and in turn operates toreverse the direction 9f the currentin the line leading from the cord 0.At the cord 0 it will be seen that the restoration of the key K afterthe call is completed bridges the relay .40 across theline, in placeofthecallin device. The current at first flows throug this relay in theproper direction to cause the closure of the circuit of. lamp 41 atSprings 259 and 260, but' when the current is reversed by the re- -.sponse of the called subscriber the armature of relay 40,'is attracted'inthe opposite direction and the lamp 41 is extin shed.

It now remains for the original calling subscriber to be'called. Thisisdone by inserting the plug P into the multiplejack j of the callinghneand operating the key K to brid e the ringer nerator across the line." Tev insertion o the plug into the jack causes the energization of thecut-ofi' winding 13 of the line switchG, as has been previouslyexplained. At thesametime the relay261 is energized over a circuitextend- .ing from ground Gr through coil 262, springs 263 and 264,sleeve contacts of ack jand plug P and relay 261 to battery. The relay261, upon'energizing, closes the circuit of lamp 265. When the receiverat station A is removed the relay 266 is energized and the lamp 265extinguished.

When the receiver at substation A is hun'gup after the conversation iscompleted the re1ay-266'deener'gizes and again lights lamp 265; When thecalled subscriber hangs up his receiver the current in relay 40 isrestored'to its original direction and the lamp 41 lighted. The operatorthen removes the .plugs P andP from their jacks, whereupon. all theapparatus used in the connection is restored to normal ositionc Theremoval of plug P from jac J breaks the circuit of the line relay 1830frepeater E, which denergize's and breaks the circuits of relay 190'and'the line relay 70 of the .connector.

The relay 70, upon deenergizing, breaks the circuit ofrelay 215, whichin turn denergizes and closes the circuit of the release magnet. 63.circuit extends from ground G through springs 216 and 223, 22 i and 267,268 and269 and magnet 63 to battery; The magnet' 63, upon energizing,

operates to, release the connector, whereupon its own circuit is brokenat the springs 268 and 269 whenthe' switch shaft reaches its lowestposition.

When the relay 190 of the repeaterE' deenergi'zes it breaks the circuitof the relay 180 ofthe selector F, whereupon the circuit of the releasemagnet 270 is closed. This circuit extends from ground G through s rings157 and160, 1 61 and 314, 271and 22,23

and 274 and magnet 270 to battery. The magnet 270 upon energizinreleases the selector'and ts; own circuit is roken at C and C (Fig. 1 toextend the connection.

to a trunk line which leads through a repeater E to a selector F (Fig.3). If the subscriber at substation A wishes to signal the operator, hethen operates his calling device for the digit corresponding to theselector level to which are connectedthe trunks H. The repeater Eoperates in the same manner as has been explained for repeater to repeatthe impulses to the selector F. The selector F operates in the samemanner as has been explained for Selector F to extend the connection toan idle trunk H. The relay 27 5 thereupon becomes energized" over acircuit extending from ground G through the lower winding of said relay,contact 276, wiper 43, thence over the heavy conductors to and throughsubstation A and back over the othersideof the line to wiper 42, thencethrough contact 277 and upper winding of relay 275-to battery. The relay275, upon energizing, operates to close a circuit from ground G throughthe lower winding of relay 278. springs 279 and 280, lower winding ofrelay 281, springs 282 and 283, 28 i and 285 and upper winding of relay278 to battery. The relay 278, upon energizing, closes the circuit oflamp 286 to signal the operator. The combined energization of relays 275 and 281 provides a. guarding potential at the selector private bankcontacts of the trunk and completes a circuit from ground G through theupper winding of relay 281, springs 287 and 288, 289 and 290, privatewiper H, side switch wiper 48, contact point 289 relay 290, contactpoint 291 and wiper 47 to the battery lead. This circuit maintains therelay 290 energized after the selector has operated. The upper windingof relay 281 has a low resistance and a small number of turns, so thatit alone will not cause relay 281 to operatively energize. its functionwill be explained later. The operator is enabled to determine thecharacter of the line calling in the following manner: It will be seenthat the circuit by means of which the switch C is held in itsoperated-position extends from ground G at repeater E through theright-hand winding of coil 292, springs 293 and 294:, 295 and 296, 297and 298, 299 and 300, winding 235 and secondary winding of inductioncoil 236 to the battery. At the repeater the lefthand winding of coil292 is included in a bridge across the conductors 300 and 301, which arenow connected through the selector F to the operators trunk. Thus, thetest tone current,fiowing from induction coil 236 .winding of relay 281.

racaaas through the right-hand winding of coil 292 induces a current inthe line which will be heard by the operator when she connects hertalking set with the line to answer the call. After the callingsubscriber has given his order to theoperator he hangs up his receiver,releasing the automatic switches brought intouse by him and the operatorsets up the desired connection by calling back onto the calling line andplugging into the called line in the reverse manner, as explainedwhensubscriber A called.

' It will be evident that the trunks leading from the switches C mightlead direct to selectors F without going through a repeater E-that is,the conductors 300 and 301 might be connected directly to the lineswitch bank springs 302 and 303. The bank spring 297 would then beconnected to the contact point 289 in the selector, and the holdingcircuit of the line switch C would then include the upper winding ofrelay 281 at the trunk H instead of the right-hand winding of coil 292at repeater E. The tone test current would then pass to the line throughthe lower In this case the operator could, if she so desired; disconnectthis tone test current from the line while conversing with the callingsubscriber. By throwingthe key K to the right the relay 278 isdisconnected from the line when the operators talking set is connectedtherewith. The relay 281 would then deenergize and cut its upper windingout of the circuit of induction coil 236, thereby removing the test tonefrom the line.

In describing how the substation A is called through the connector L itwas assumed that the called line was idle. In case the called line hadbeen busy the connector L would not have completed connection with theline and the operator would have been given a busy signal as follows:Whenever a line is busy there is a guarding ground potential on itsconnector private bank contacts. When the wiper 59 engages a contactwhich is thus grounded a circuit is completed through side switch wiper68 (which is then in second position), contact point 305 and lowerwinding of relay 306 to battery. The relay 306, upon energizing,completes a circuit from ground G through the springs 307 of the relay215, springs 308 and upper winding of the relay 306 and private magnet62 to battery. This circuit maintains the private magnet energized afterthe slow relay 226 deenergizes. Since the private magnet does notdenergize after the last digit is called, the side switch remains insecond position and connection is not completed with the busy line. Therelay 306 is also locked through its upper winding independently of theguarding potential at the private bank contact, and in its energizedposition the relay 306 comcircuit from the busy signaling machine 309,side switchwiper 67 (in second position), thence over the heavyconductors to .the'cord '0, through the talking set, or

through the cord to the calling line, as the case might be, andback overthe other side of the line, through the upper winding of the connec orline relay 70 toythe battery lead 227 and thence back to the machine N.The apparatus is released from this position in the same manner as whenan idle line is called.

In Figs. 8 and 9 there is shown a connection established through themedium of ap paratus embodying the same principles as embodied in Fig.-1, with the exception that in Figs. 8 and 9 the operator is notified ofthe character of the calling line by a visual rather than by an audiblesignal. The substation A is shown provided with a meter R which iscontrolled by the operator at the central office through the medium ofthe magnet 320. The line A is shown without a meter. The circuits of theline switches C and C of the lines A and A are so arranged that when theline A? calls, the

.tact. Theengagement of the'springs lamp 321 at the operators cord Twill be lighted, but when the line-A calls, the lamp 1 will not-belighted. The line switch C difl'erssomewhat from the line switch C(Fig. 1) in that the line. and cut-01f relays are separated from the'switch proper. These relays are very similar in their connections andfunctions to theusual line and cut-ofl relays in manual switchboardsystems and, if desired, may be located on the manual board in the usualmannerinstead of on the switch C.

When the subscriber at substation A re-' -moves his receiver from thehook tory to making a call; a circuit is c osed. extending from groundG" through the re arasprings 324 and 325 of the cut-01f relay323, lineconductor 326, switch hook, transmitter and receiver at. thesubs-tationA, line 327,

s rin s 32s and329 and line relay 322 to the battery lead 330, thencethrough the battery B to ground G. The relay'322, upon energizing,completes a circuit extending from ground G through springs 331 and 332,windings 333 and 334 of switch 0, springs 335 and 336, contact point 338and armature point 361 and armature 362 to the batterylead 330. Thewinding 349, upon energizing, attracts the plunger arm of theswitch Gwhich operates to extend the connection to the cord circuit T. As soonas connection is extended to the cord T the relays 365 and 366 areenergized over a circuitzextending from ground Q through relay 365,trunk conductor 367, springs 368 and 369, 342 and 341, thence to andthrough the substation and back over the other side of the line,

through springs 343 and 344,370 and 371;, and relay 366 to the batterylead 330. The relay 366, upon energizing, completes a circuit for theanswering supervisory lamp 363, said circuit extending from ground G.through springs 372 and 373, 374 and 375 and lamp363 to the batterylead;

It will be seen that when connection is extended to the cord T a circuitis also closed for the cut ofi relay 323 of the calling him, thiscircuit extending from ground G through said relay 323, springs 347 and348 of switch C, springs 37 6 and 377 of switch 0' and resistance 378 tobattery.- The relay 323, upon "energizing, operates to disconnect therelay 322 from the line, which relay thereupon deenergizesganddisconnects the ground G from the switches C and C After this ground Gis disconnected,

' switches C and C are maintained in their operated positions by acircuit which extends irom ground G? at the cord T through lamp 321,springs 379 and 380 of relay 381, springs 382 and'383 of relay 365,relay 384,

andspring's 385 and 386, thence one branch of'the circuit extendsthrough the winding 349 of switch C springs 351 and 353 and winding 486to battery, while a second. branch passes through the springs 346 and345 ofthe switch 0 and-through the windsame manner as explained for themaster switches D and D. The relays 390'and 391, which correspond to therelays'122 and 125 in. Fig. 1, are energized by the same ground G whichcompletes the holding circuit for the switches C and G It has now beenexplained how" the switches-Cand Care operated to extend connection toacord T and the answering supervisory lamp 363 is lighted. When thisoccurs the operator operates the key K Fig, 9) to connect the operatorsset Siwith' t ecord and inquires the line wanted;

receiving the number, the operator restores the key K and inserts theplug P into the jack J of the line called for. circuit 1s thereuponclosed from ground G through the cut-off relay 392 of line A sleeveconductors of jack J and plug P conductor 393, lamp 394 and relay 395 tobattery The relay 392 is energized over this circult to disconnecttherelay 396 from the line, lamp 391 is lighted and relay 395 operatesto break the circuit'of lamp 363. I The operator rings thecalledsubscriber by pressing the key K to the right to bridge the generatoracross the line in the usual manner. \Vhen the called subscriberanswers, a circuit is closed from ground Gr atthe cord T, through relay397, conductor 398, plug P and jack J .line 399, transmitter andreceiver at substation A line 400, jack J 6 and plug P", conductor 401and impedance coil 402 'to battery. The relay, 397, upon energizing,closes a shunt, around lamp 394, which thereupon ceases to glow tosignify to the operator that the called subscriber has answered. It willbe 'remen ibered that the lamp 321 in the operators cord was lightedwhen connection was first extended to the cord. This, signifies to theoperator that the calling line is provided with a meter. In order torecord the connection on the meter R the operator momentarily depressesthe key K. It will be seen thatthe l'eft-handwinding of the meter magnet320 of the callingline is included in circuit in multiple withthecut-off relay 323 and, therefore, in serieswith the resistance 378 atthe cord T. This resistance does not permit suflicient current'to flowto operate the magnet 320. hen the key K is depressed, however, themagnet 320 is connected with the battery B through the magnet 403. Thispermits the magnet 320 to operate and also energizes the magnet 403. Themagnet 320, upon energizing, operates the meter R and closes the circuitof its own right-hand winding so that it remains in its operatedposition afterthe key K is opened. The magnet 403, upon energizing,makes a duplicate record of the call on the meter R and also connectsthe relay 381 in multiple with the lam 321. The relay 381, uponenergizing, isconnects the lamp 321 and leaves itself in an energizingcircuit extending from ground G through the relay 38-1, springs 404 and380 and thence to battery through the switches C and C as traced for thelamp 321. It is thus seen that the lamp which signifies to the operatorthat the calling line is a metered line is extinguished as soon as thecall is registered.

When the conversation is completed the operator is given one disconnectsignal when the called subscriber hangs up his receiver, therebybreaking the circuit of the relay 397,

which deenergizes and removes the shunt of the lamp 396 and the relay395 at the cord, The relay 395, upondeenerglzing, breaks the circuitoflamp 363 and opens the holding circuits of the switchesC and G whichthereuponallow their plungers to be withdrawn from their banks; The release of the switchesC and C breaks the circuits of the cut-off relay323 and of the metenmagnet 320, and all apparatus employed in theconnection is restored to normal position.

It having been explained howthe lamp 321 is lighted to signify to theoperator when a call comes from a line having a meter, it will now bepointed out what changes may be made in the equipment of lines whichhave 'no meter in order thatthis lamg shall not light when a call comesfrom su' beseen, that when the subscriber A makes a call the lamp 321 atthe seized operators cord is connected to battery at the switch Cthrough the two ,windings of said switch in series, instead, oftinmultiple as in the case offthe switch 0*. This does 'notp'erinitsufiicient current to flow through the lamp .321 to ,cause it to, glow;It will be seen'that, although; as shown in the drawhugs, the lamp 321is lighted when the line with the meter calls, and is not, lighted whenthe line without a meter calls, the meter itself has nothing to" do withthe discriminating operation of said lamp.

The cord T is pr'ovidedwith a key K. The function of this keyis tb put aguarding potential on the. master switch bank contact of its trunk iffor any reason it is desired that no calls shall come in over thistrunk. It is evident that when the key is operated the'springs 410 and411 operate in the same manner as the springs 382 and 383 of therelay365 to connect the ground G with the master switch contact point 412.Since this provides the contact point 412 with a guarding potentialwithout energizing the relay 384, the key K is provided with a pair ofsprings 417 which performthe same function as said relay. It should bestated here that the ground Gr which is shown connected with the key K",and therefore with a spring of the relay 384, would be omitted on allexcept the end relay of the chain which controls the relay 413, sincethe circuit of this relay is to be closed only when all the relays 384of the series are energized, or the keys K corresponding thereto areoperated. In case it is desired to decrease the number of operators onduty during periods of light load, certain operators may leave theirpositions, and by depressing all the keys K thereat may prevent anyfurther calls from coming in on their trunks and thus concentrate allthe trafiic upon the remaining operators.

' gized to close thecircuit of the starting. re-

As shown herein, the o erators cord T is provided with a meter 2 whichmay be used to keep count of ineffective calls or .for any other purposedesired.

rom the foregoingit will be seen that theoperator may know instantlywhen answering the call whether the same is from a measured service aline or one of opposite character. There are, it will be seen,-as manydifferent indicating expedients as there are different kinds of lines.The absence of any signal at all may be the expedient for'indicatinglines of one character.

What I claim as my invention is 1. In a telephone system, lines equippedfor giving measured service, lines equipped for iving unmeasuredservice, a manual switc board at which calls from said lines areanswered, and automatic means for indicating to the operator thecharacter of the line calling.

2. In a telephone system, a lurality of telephone lines of different kin5, means by which an operator may answer calls from an of said lines,and automatic means for in icating to the operator upon-answering thecharacter of the line calling.

3. In a telephone system, lines equipped,

switchboard at which calls from said lines are answered, and automaticmeans for indicating to the operator the character of the line calling,some of said lines having trunking switches with coils allotted thereto,and said automatic means comprising circuits that include coil of'saidswitches.

6. In a telephone system, a lurality of telephone lines of different kins, means by which an operator may answer calls from any of said lines,and automatic means for indicating to the operator the character of thelinecalling, some of said lines having trunking switches with coilsallotted thereto, and'said automatic means comprising circuits thatinclude coils of said switches.

7. In a telephone system, lines equipped for giving measured service,lines equipped for giving unmeasured service, a manual switchboard atwhich calls from said lines are answered throu h the medium of areceiver and a centra ized source of current,

means for indicating to the operator the cal in? line.

- 8. n a telephone system, lines equipped for giving measured service,lines equipped for iving unmeasured service, a manual switc board atwhich calls fromsaid lines are answered through the medium of a receiverand a central batter means common to a plurality of lines or indicatingto the operator the character of the line calling, trunks leading to theoperators position, and switches for automatically connecting callinglines to idle trunks.

9. In a telephone system, a plurality of telephone lines of differentkinds, means comprising a receiver and a central battery .bywhichanoperator may answer calls from any of said ll'nes,-means commonto a plurality of lines, for indicating to the operator upon answerinthe character of the line calling, trunks eadin to the operatorsposition, and switches or automatically connecting calling lines to idletrunks.

10. In a telephone system, lines equipped for giving measured service,lines equipped lit) for giving unmeasured service, a manual switchboardat which calls from said lines are answered through the medium of areceiver and a central battery, means common to a plurality oflines forindicating to the operator the character of the line calling, andautomatic switches controlled over the two sides of the calling line inseries.

11. In a telephohe system, a plurality of telephone lines of differentkinds, means comprising a receiver and a central battery by which anoperator may answer calls from any of said lines, means common to aplurality vof lines for indicating to the operator upon answering thecharacter of the line calling, and automatic switches controlled overthe two sides of the calling line in series.

12. In a telephone system, lines equipped for giving measured service,lines equipped for giving unmeasured service, a manual switchboard atwhich calls from said lines are answered through the medium of areceiver and a central battery, means common to a plurality of lines forindicating to the operator the character of the line calling, and meansautomatically controlled by the operator for extending a callingconnection to the called line.

13. In a telephone system, a plurality of telephone lines of diiferentkinds, means comprising a receiver and a central battery by which anoperator may, answer calls from any of said lines, means common to aplurality of lines for indicatin to the operator the character of'theline ca 'ng, and means antomatically controlled by the operator forextending a calling connection to the called line.

it. In a telephone system, lines equipped for giving measured'service,lines equipped for giving unmeasured service, a manual switchboard atwhich calls from said lines are answered through the medium of areceiver and a central source of electrical energy, means common to aplurality of lines for indicatin' to the operator the character of theline ca ing, said central source of electrical energy for supplyingtalking current to mid lines.

15. In a telephone system, lines equipped for givinganeasured service,lines equipped for iving unmm'sured service, a manual switc board atwhich calls from said lines are answered through the medium of areceiver and a central battery, means common loin plurality of lines forindicating to the operator the character of the line calling, andsignals by which calling subscribers indicate to the operator that aconnection is wanted. said signals being each common to a plurality oflines.

16. In a telephone system, a plurality of telephone lines of difierentkinds, means ocanprising a receiver and a wntral battery menses by whichan operator may answer calls from any of said lines, means common to aplurality of lines for indicating to the operator upon answering thecharacter of the line calling, and signals by which calling subscribersindicate to the operator that a connection is wanted, said signals beingeach common to a plurality of lines.

17. In a telephone system, lines equipped for giving measured service,lines equipped for giving unmeasured service, a manual switchboard atwhich calls from said lines are answered through the medium of areceiver and a central battery, means common to a plurality of lines forindicating to the operator the character of the line calling, flexibleconnecting cords on said board, and means controlled over calling linesfor automatically selecting idle cords.

18. In a telephone system, a plurality of telephone lines of difi'erentkinds, means comprising a receiver and a central battery by whi h anoperator may answer calls from any of said lines, means common to aplurality of lines for indicating to the operator upon answering thecharacter of the line Calling, flexible connecting cords at theoperators position, and means controlled over calling lines forautomatically selecting idle cords.

19,. In a telephone system, a plurality of subscribers lines ofdifferent characters, a manual switchboard at which calls from saidlines are answered through the medium of a receiver and a centralbattery, a plurality of trunlrs extending between said lines and saidswitchboard, an automatic switch for selectmgan idle trunk, andsignaling apparatus associated with said switch for indicating to theoperator the character of the line callmg, said apparatus being commonto a plurality of said lines.

201 In a telephone system, a plurality of subscribers lines of differentcharacters, a manual switchboard at which calls from said lines areanswered, a plurality of trunks extending between said lines and saidswitchboard, a non-numerical switch individual to the suhscriberslinesfor selecting an idle trunk, and a signal associated with said switchfor indicating to the operator the character of the line calling.

21. In a telephone system, a lurality of subscribers lines of different0 aracters, a manual switchboard at which calls from said lines areanswered, a signal common to a plurality of said lines by which thecalling subscribers indicate to the operator that a connection isdesired, and a second si al individual to said lines for indicating thecharacter of the line'calling.

22 In a telephone system, a plurality of subscribers lines of differentcharacters, a manual switchboard at which'calls from said lines areanswered, trunk lines extending hecommon to a plurality of said lines bywhich calling subscribers indicate to the operator that a connection isdesired.

23. In a telephone system, a lurality of -aracters, a manual switchboardat which calls from said lines are answered, a lurality of trunk linesextending between said calling lines and said switchboard, an automatictrunk-selecting switch for selecting an idletrunk, an operating magnetforsaid switch, and a tone test having'a coil connected in series with awinding of said operatin magnet for producing a tone test to in icatetothe operator the character of the line calling.

24. In a telephone system, a plurality of subscribers lines of differentcharacters, a manual switchboard at which calls from said lines areanswered, a plurality of trunk lines extending between said callinglines and said switchboard, an automatic trunk-selecting switchforselecting an idle trunk, an'operating magnet for said switch, a tonetest having a coil connected in series with a winding of said operatingmagnet for producing a tone test, and means for transmitting said toneover a third conductor of the selected trunk to indicate to the operatorthe character of the line calling. Y

25. In a telephone system, a plurality of subscribers lines, a manualswitchboard, trunk lines leadingto said switchboard, and means includingprimary and secondary nonnumerical trunk-selectingswitehes forautomatically extending theconnection from a snbscribers line to an idletrunk extending to said switchboard.

26. In a telephone system, a plurality of subscribers". lines, a manualswitchboard, non-numerical switches individual to said subscriberslines, trunk lines extending from said switches, means controlled bysaid switches for connecting said subscribers lines with an idle one ofsaid trunks, seeondary non-numerical switches at the opposite end ofsaid trunks, trunk lines terminating in said manual board, and meanscontrolled by said secondary non-numerical switches for extending theconnection over an idle trunk to said manual switchboard.

27. In a telephone system, a plurality of ups, a manual switchboard, aplurality of links extending to different sections of said board andterminating in manually-controlled terminals, and

automaticall -operated trunk-selectingmechanism opera le for connectingthe links w th the lines upon two consecutive non-numerical trunkingoperations;

28. In a telephone system, a non-numerical trunk-selectin switchcomprising separate and distinct ii a separate operating magnet, saidoperating magnet comprising a pull-down winding and a hold-down winding.

. 29. In a telephone system, anon-numerieal switch, a. trunk line, and aplunger operated by said switch for connecting with an idle trunk, saidswitch comprising a separateline and cut-oil relay and a separateoperating magnet, said operating magnet comprising a winding foroperating said plunger and asecond holding winding for maintaining. saidplunger in operated position. 30. In a telephone system, a plurality oftelephone lines of different, kinds, means in eluding automatic switchesand an operators board for establishing a connectionbetween twdfof saidlines, means comprising a receiver and a central battery by which anoperator may answer calls from any of said lines, and means common to aplurality of said lines for indicating to the operator the character ofany line calling.

31. In a telephone system, a plurality of telephone lines of differentkinds, means comprising a receiver and a central battery ne andcut-ofirelays andv by which an operator may answer calls from ator theeharacterof any line calling, and

automatic switches controlled over the two sides of the calling line inseries.

33. In a telephone system, a plurality of telephone lines of differentkinds, means comprising a receiver and a central battery by which anoperator may answer calls from any of said lines, and means common to aplurality ofsaid lines electrically associated with the terminal of theline at the central ofiice for indicating to the operator the.characterof the line calling, said means comprising mechanism for producing anaudible signal when the operator answers the call.

34'. Ina telephone system, lines equipped for giving measured service,lines equipped for iving unmeasured service, a manual swit'eiboard atwhich calls from said lines are answered through the medium of a reeeiver anda central batte and means common to a plurality of Sal lineselectrically associated with the terminal of the line at the centraloifice for indicating to the oper- 1&1

